CFTR does not alter acidification of L cell endosomes.

Endosomes from L cells, transduced with the CFTR gene, and the parental line, which does not express detectable levels of CFTR, were loaded with FITC-dextran, isolated and the initial rates of acidification, steady-state pHi, and proton leak rates were compared over a range of chloride concentrations (0-140 mM). Values for these parameters were similar for endosomes from both cell lines in the presence and absence of cAMP and PKA. These results indicate that CFTR does not alter L cell endosome acidification, possibly due to an adequate intrinsic CI- conductance or to a failure to incorporate sufficient functional CFTR or a necessary co-factor in endocytic membranes.